It is known that a voltage emission or shunt trip is currently used for causing the opening of a circuit-breaker by means of a control device situated at a distance.
Likewise, an undervoltage trip is currently used for causing the opening of a circuit-breaker as a safety means when the voltage of the mains falls below a certain level. Such tripping devices comprise, generally, a striker operating a tripping element of the circuit-breaker and operative as a function of an electromagnet which exerts magnetic attraction by energizing of the control winding, in the case of a voltage emission tripping device or a tripping device which effects release by de-energizing of the control winding in the case of an undervoltage trip. These tripping devices are therefore different according to whether the tripping device is of the type which exerts magnetic attraction or of the type which effects release.
It is therefore compulsory, more particularly in a maintenance service, to have tripping devices of both types.